DESCRIPTION (Principal Investigator's Abstract): A nutrition assessment tool will be developed, implemented, and evaluated for use in the treatment and prevention of obesity. The system will consist of a hand-held calculator which estimates dietary intake and calculates energy expenditure; and a computer interface designed to download and display data from the calculator. Principles of behavioral change including immediated feedback on goal attainment and response-contingent positive reinforcement and instruction will be incorporated by auditory prompts and messages displayed on the calculator screen. This prototype will provide an innovative means to continuously monitor diet and exercise habits, enhance compliance with treatment regimens, and support lifestyle changes in diet and physical activity. The instrument will be field tested with 3 test groups for 9 weeks. Compliance to dietary and exercise regimens will be statistically analyzed and compared between subjects using the calculator method and counseled with the interface system, and subjects using the pencil-and-paper method. Feedback will be obtained by questionnaire and focus groups. Results will be evaluated and recommendations made for a more refined, comprehensive, and technologically advanced system. Potential applications are foreseen in clinical, community, and research settings, and with free living populations.